In his 1919 best-selling book _A Man for the Ages: A Story of the Builders of Democracy_, about Abraham Lincoln, Bacheller gives this word to Mrs. Lukins, a person who does not seem to fit any of proposed ethnic associations with the word (in Cajun French, Italian, and Hebrew proposed origins). Mrs. Lukins describes a friend of Lincon admiringly: “‘Stout as a buffalo an’ as to looks, as ye might say, real copasetic.’ Mrs. Lukins expressed this opinion solemly and with a slight cough. Its last word stood for nothing more than an infinite depth of meaning.” (p. 69) Bacheller explains the new word.

Page 287: “There was one other word in her lexicon [suggesting it may not be in the readers' lexicon yet] which was in the nature of a jewel to be used only on special occasions. It was the word ‘copasetic.’ The best society of Salem Hill understood perfectly that it signified an unusual depth of meaning.”

Page 401: “In the words of Mrs. Lukins [on a fine meal at home] ‘it is very copasetic.’”

The word we are introduced to reportedly has “depth.” Mrs. Lukins has another another special, prized word–unique to her–that also had depth: “coralapus” (pages 212 and 286). The latter is quite probably a newly-made word (I haven’t found it anywhere else). Perhaps “copasetic” was too, the difference being that
only one of them caught on.

Stephen Goranson
http://www.duke.edu/~goranson
“…for the whole nine yards.” E.S. Land, 1942

p.s. The full text of the Bacheler’s book is available online at http://www.gutenberg.org

more text:

Page 212:
“A little whitewash wouldn’t hurt it any,” said Abe. “I’ll gladly give him my title of Captain if I could unhitch it someway.”

“Colonel is a more grander name,” she insisted. “I call it plum coralapus.”

She [Mrs. Lukins] had thus expressed her notion of the limit of human grandeur.”

Page 286:
[Mrs. Lukins:] “He’s a good man. there don’t nobody know how deep an’ kind o’ coralapus like he is.

She now paused to count stitches. For a long time the word “coralapus’ had been a prized possession of Mrs. Lukins. Like her feathered bonnet, it was used only on special occasions by way of putting her best foot forward. It was indeed a family ornament of the same general character as her husband’s title. Just how
she came by it nobody could tell, but of its general significance, as it fell from her lips, there could be no doubt whatever in any but the most obtuse intellect. For her it had a large and noble, although a rather indefinite
meaning, entirely favorable to the person or the object to which it was applied. [/page 287] There was one other word in her lexicon [...as above, copasetic].”